In this article, in the context of the fiftieth anniversary of H. L. A. Hart’s The Concept of Law, I reconsider the moderate indeterminacy of law thesis, which derives from the open texture of language. For that purpose, I intend: first, to analyze Hart’s moderate indeterminacy thesis, i.e. determinacy in “easy cases” and indeterminacy in “hard cases,” which resembles Aristotle’s “doctrine of the mean”; second, to criticize his thesis as failing to embody the virtues of a center in between the vices of the extremes, by insisting that the exercise of discretion required constitutes an “interstitial” legislation; and, third, to reorganize an argument for a truly “mean” position, which requires a form of weak interpretative discretion, instead of a strong legislative discretion.